$ \left(\dfrac{3}{4}\right)^{-3}$
Answer: $= \left(\dfrac{4}{3}\right)^{3}$ $= \left(\dfrac{4}{3}\right)\cdot\left(\dfrac{4}{3}\right)\cdot \left(\dfrac{4}{3}\right)$ $= \dfrac{16}{9}\cdot\left(\dfrac{4}{3}\right)$ $= \dfrac{64}{27}$